Cathode disintegration



Patented July 14, 1936 PATENT OFFICE CATHODE DISINTEGRATION PaulAlexander, Brussels, Belgium, minor to La Dispersion Cathodique (en abrgDisca) S. A.,

Brussels, Be l No Drawing. Application November 1, 1934, Serial No.751,092. In France October 16, 1934 6 Claims.

The present invention relates to an improved process of cathodedisintegration.

Metallic layers'obtained by cathode disintegration upon smooth supportssuch as glass, porcelain, enam'el, e'tc., have in general this drawbackthat they are not veryv adherent and that they do not withstand electriccharges when the layer is inserted in an electric circuit as an electricresistance such as a heating element, etc.

The object of the invention is to obtain by cathode disintegrationstrongly adhering and resisting metal layers.

The invention is characterized in that a hard metal of the iron ortungsten groups (periodic system) is first deposited by cathodedisintegration upon a suitable support, and afterwards another metal,which would not give by itself a sufficiently adherent and resistantlayer, is deposited by cathode disintegration upon the first metal. Hardmetals according to the present invention are metals such as Fe, Co, Ni,Mo, W and Cr.

It has been found that such a layer is strongly adherent and has a highmechanical and electrical resistance.

It has been found moreover that the chemical resistance is increased ifthe'metal deposited in the second place is a metal of the preciousmetals group; Pd, Pt, Ir, Rh, Au, Ag.

Moreover, it is possible to increase the resistance of the layerproduced if the dispersion is eilected upon a support heated at a hightemperature (the support being heated either in a direct or in anindirect manner) and preferably with a high voltage current. It has beenascertained that in this manner the combined layer obtained is analogousto an alloy of the two metals which have been deposited. A combinedlayer nickel-platinum for instance, has all the advantages of a nickellayer and at the same time is much more passive to oxidation. The sameremark applies to layers of cobalt and platinum, of molybdenum andplatinum. Excellent results are obtained with chromium and platinum orwith chromium and iridium.

It is also possible to apply the present invention to the production ofheating plates capable of withstanding a surface temperature of from 350C. to 450 0., without the necessity of protecting themetal layers.Thanks to the present invention, it will be possible in many cases touse plates, instead of wires, as electric resistances. Whilst a layer ofplatinum would crack if subjected to an electric current of one watt persquare centimeter of surface, a combined layer of a hard metal andplatinum according to the present invention can withstand charges of tenwatts per square centimetre, or more.

As a suitable support according to the present invention, use may bemade of a substance having a smooth surface, without pores, capable ofwithstanding high temperatures without breaking or cracking. Assubstances particularly suitable, the following may be cited: enamelmetal plates, quartz which has been molten, certain kinds of enamelledporcelain. In certain cases, where the temperature should not be toohigh, glass may also be used.

Example of carrying the invention into effect:

A layer of nickel of ten millimicrons is first deposited upon a suitablesupport by cathode disintegration. A layer of platinum of twentymillimicrons is afterwards deposited upon the first, the support beingheated between 200 and 300. C., and the voltage used being 2400 volts.

The layer thus obtained does not dissolve in sulfuric acid, or inhydrochloric acid, nor in concentrated nitric acid and it does notbecome oxidized, even at high temperatures. Moreover, the said layer isa better conductor of electricity than a layer consisting of theprecious metal alone and having the same thickness. The combined layercan be removed from its support with diflficulty only, and does notcrack easily.

It was not possible so far to obtain well adhering mirrors, silveredmirrors for instance, by cathode disintegration. Thanks to the presentinvention it is possible to deposit first a layer of nickel or ofmolybdenum upon a suitable support, and to deposit afterwards a. layerof silver; a mirror is thus obtained having a strongly adhering layer ofsilver. i

. The'layers obtained according to the present invention will beutilized with advantage in all the cases where it is desired to obtain alayer of high mechanical, electrical and/or chemical resistance;

I claim:

1. A process of coating objects having hard, smooth, non-metallicsurfaces, which comprises first depositing upon such surfaces by cathodedisintegration a layer of a metal selected from the metals of the ironand tungsten groups of the periodic system, and then depositing bycathode disintegration upon said first layer a layer of a differentmetal which is strongly adherent to the first metal to form a coatinghaving high resistance to injury by chemical, mechanical or electricalinfluences. 55

2. A process of coating objects having hard, smooth, non-metallicsurfaces, which comprises first depositing upon such surfaces by cathodedisintegration a layer of a metal selected from the metals of the irongroup of the periodic system, and then depositing by cathodedisintegration upon said first layer a layer of a different metal whichis strongly adherent to the first metal to form a coating having highresistance to injury by chemical, mechanical or electrical influences.3. A process of coating objects having hard, smooth, non-metallicsurfaces, which comprises first depositing upon such surfaces by cathodedisintegration a layer of a metal selected from the metals of thetungsten group of the periodic system, and then depositing by cathodedisintegration upon said first layer alayer of a different metal whichis strongly adherent to the first metal to form a coating having highresistance to injury by chemical, mechanicalor electrical influences.

4. A process of coating objects having hard, smooth, non-metallicsurfaces, which comprises first depositing upon such surfaces by cathodedisintegration a layer of a metal selected from the metals of the ironand tungsten groups of the periodic, system, and then depositing bycathode disintegration upon said first layer a layer of a precious metalwhich is strongly adherent to the first metal to form a coating havinghigh resistance to injury by chemical, mechanical or electricalinfluences.

5. A process of coating objects having hard, smooth, non-metallicsurfaces, which comprises first heating said surfaces and depositing onsuch heated surfaces by cathode disintegration a layer of a metalselected from the metals of the iron and tungsten groups of the periodicsystem, and then depositing by cathode disintegration upon said firstlayer a layer of a different metal which is strongly adherent to thefirst metal to form a coating having high resistance to injury bychemical, mechanical or electrical influences.

6. A process of coating objects having hard,

- smooth, non-metallic surfaces, which comprises coating having highresistance to injury by chem- 25 ical, mechanical or electricalinfluences.

PAUL ALEXANDER.

